The Vertical grip in the 5d mark III is about third an inch wider than the 1D series!

People say it's the battery and stuff. But when I put the 5d mark III tray along side the 1d mark II battery, it is very clear that they are both the same size. So, why did they did have to make it this wide?

I shoot for hours a day and I still don't feel comfortable when moving from the 1d to the 5d.